The class implements a buffered output stream. By setting up such
an output stream, an application can write bytes to the underlying
output stream without necessarily causing a call to the underlying
system for each byte written.

write

Writes len bytes from the specified byte array
starting at offset off to this buffered output stream.

Ordinarily this method stores bytes from the given array into this
stream's buffer, flushing the buffer to the underlying output stream as
needed. If the requested length is at least as large as this stream's
buffer, however, then this method will flush the buffer and write the
bytes directly to the underlying output stream. Thus redundant
BufferedOutputStreams will not copy data unnecessarily.